Modern control systems are growing in application and complexity. There are many classes of control systems, with many variations and combinations. Some control systems generate signals that control components of a device. For example, some automobile engine control systems generate signals that directly or indirectly control various components (e.g., spark plugs, fuel injectors, etc.) of an internal combustion engine. The present invention will be described with reference to an automobile engine control system, it being understood that the present invention should not be limited thereto.
The simplest engine control systems only control the timing and quantity of fuel injected into each cylinder during each cycle of the engine. More advanced engine control systems found in modern cars also control ignition timing, variable valve timing, the level of boost maintained by a turbo charger, etc. Using a complex set of algorithms, engine control systems can determine the quantity and timing of fuel injected into cylinders, ignition timing, and other needed parameters by monitoring the engine through sensors that include, for example, a manifold absolute pressure sensor, throttle position sensor, air temperature sensor, oxygen sensor, etc.
The use of the same reference symbols in different drawings indicates similar or identical items.